A confocal scanning microscope system taking measures to avoid problems caused by lateral chromatic aberration of the objective lens has been known. There have been disclosed, for example, a configuration in which lateral chromatic aberration is reduced by a whole system combining a scanning optical system with an objective lens system such that lateral chromatic aberration of the objective lens system is canceled out by a scanning optical system provided between the objective lens system and a scanning mechanism (see, for example, Japanese Patent Application Laid-Open No. 5-72481), and a configuration in which effects of lateral chromatic aberration generated in different wavelength regions are reduced by providing a plurality of correction optical systems corresponding to respective different wavelength regions (see, for example, Japanese Patent Application Laid-Open No. 5-341192).
In a recent objective lens, lateral chromatic aberration is corrected to an extent that there are practically no problems over relatively large wavelength region, so that only a specific wavelength region (ultraviolet wavelength region) where lateral chromatic aberration is not corrected becomes a problem. The configuration disclosed in Japanese Patent Application Laid-Open No. 5-72481 cannot correct lateral chromatic aberration in this specific wavelength region, and the configuration disclosed in Japanese Patent Application Laid-Open No. 5-341192 becomes complicated since a plurality of correction optical systems have to be used.